1666447 has 2 divisors, whose sum is σ = 1666448. Its totient is φ = 1666446.

The previous prime is 1666429. The next prime is 1666477. The reversal of 1666447 is 7446661.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666447 - 2¹⁵ = 1633679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833223 + 833224.

It is an arithmetic number, because the mean of its divisors is an integer number (833224).

2^1666447 is an apocalyptic number.

1666447 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666447 is an equidigital number, since it uses as much as digits as its factorization.

1666447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 34.

The square root of 1666447 is about 1290.9093693982. The cubic root of 1666447 is about 118.5579010482.

The spelling of 1666447 in words is "one million, six hundred sixty-six thousand, four hundred forty-seven".